Thanks for sharing your concern and resorting solution to help fix the issue, @SconetBryan.

There's an open investigation with QuickBooks (Desktop) when sending an invoice emails to outlook. Our product engineers are aware of this issue, and are now working hard to fix this the soonest.
 
I recommend giving our Customer Care Team a call to add your account details to the list of affected users. This way, you'll be updated as soon as a fix is implemented.
 
Here's how to contact support:

1. Go to the Help icon and select QuickBooks Desktop Help.
2. Select Contact Us.
3. Give a brief description of your issue, then select Continue.
4. We’ll provide you a few support options. Select which one is best for you.

You can always post here if you have more questions.